The objective of this study is to evaluate a new approach to anticoagulation therapy, utilizing a unique software application and workflow redesign. Anticoagulation therapy, as it is currently administered in the United States, too often fails to achieve therapeutic goals, while giving rise to a large number of potentially preventable medical complications. Improvements in quality of care and clinical outcomes have been demonstrated by the use of specialized anticoagulation clinics. Implementation of these clinics, however, has been severely limited by their expense and the degree of subspecialty expertise required. The approach to be evaluated utilizes a software application that enables a subspecialty level of care to be rendered in a primary care setting, combined with changes in workflow that simultaneously improve financial performance. The activities outlined in Phase 1 are designed to measure the impact of this combination on the administration of anticoagulation therapy in a primary care setting, with attention to quality of care indicators and financial performance. Phase 2 will expand the use of this approach in an integrated fashion to multiple primary care sites as well as emergency departments and inpatient settings. Phase 2 will monitor indicators similar to those of Phase 1, as well as the use of this approach to facilitate outpatient treatment of deep venous thrombosis.